Sample transfer device and method for analytical system

ABSTRACT

An apparatus for chemical treatments has an enclosed vessel provided with lines for conveying samples and selectively openable valves in communication with sources of gases at atmospheric, increased, and reduced pressures. A plurality of such vessels may be combined, instead, in which case the pressure of the atmosphere in each vessel is made higher than that in the following vessel, so that the sample can be transferred to the following vessels. The vessel or vessels may be equipped with means for agitation, fixed-quantity sampling, liquid level detection, washing, filtration, extraction, thermostatic control, aeration, thermal concentration and distillation. An additional vessel equipped with pH-adjusting means and capable of maintaining an atmospheric pressure inside may be installed.

United States Patent 11 1 Takano et a1.

[ Dec. 30, 1975 1 1 SAMPLE TRANSFER DEVICE AND METHOD FOR ANALYTICAL SYSTEM [75] Inventors: Nobuyoshi Takano, Katsuta; Kaoru Sakai, Hitachi; Satoshi Aoki; Kazuo Yasuda, both of Katsuta, all of Japan [73] Assignee: Hitachi, Ltd., Japan [22] Filed: Aug. 28, 1973 21 Appl. No.: 392,294

[30] Foreign Application Priority Data Sept. 14, 1972 Japan 47-91731 [52] US. Cl 23/259; 23/253 R; 23/230 R;

73/4254 R; 137/572; 141/54 [51] Int. Cl. G01N 1/14 [58] Field of Search 23/259, 253 R, 230 R, 260; 137/572, 14, 205, 206,154, 209; 417/121, 122; 141/4, 5, 50, 54, 56,134/22-R, 37;

3,551,111 12/1970 Carlson 23/253 R 3,557,077 l/l971 Brunfeldt et a1 23/259 X 3,631,012 12/1971 Zapf et a1. 23/285 X 3,647,390 3/1972 Kubodera et a1. 23/259 X 3,684,452 8/1972 Bessman 23/259 X 3,713,778 1/1973 Karamian 23/259 3,717,435 2/1973 Ertl et a1. 1 23/253 R X 3,740,320 6/1973 Arthur 1 23/253 R X 3,773,469 11/1973 Hiser et a1 23/253 R 3,791,221 2/1974 Kirschner et al. 23/253 R X 3,836,329 9/1974 Jordan 23/230 R Primary Examiner-R. E. Serwin Attorney, Agent, or Firm-Craig & Antonelli [57] ABSTRACT An apparatus for chemical treatments has an enclosed vessel provided withlines for conveying samples and selectively openable valves in communication with sources of gases at atmospheric, increased, and reduced pressures. A plurality of such vessels may be combined, instead, in which case the pressure of the atmosphere in each vessel is made higher than that in the following vessel, so that the sample can be transferred to the following vessels. The vessel or vessels may be equipped with means for agitation, fixedquantity sampling, liquid level detection, washing, filtration, extraction, thermostatic control, aeration, thermal concentration and distillation. An additional vessel equipped with pH-adjusting means and capable of maintaining an atmospheric pressure inside may be installed.

US. Patent Dec. 30, 1975 Sheet 1 of 12 3,929,411

I PRIOR ART FIG.

FIG. 2 PRIOR ART FIG. 3 PRIOR ART U.S. Patent Dec. 30, 1975 Sheet 2 of 12 3,929,411

FIG. 4 PRIOR ART +-T k 26a 27 26b 27 26c US. Patent Dec. 30, 1975 Sheet 3 of 12 3,929,411

FIG.5 PRIOR ART US. Patent Dec. 30, 1975 Sheet4 of 12 3,929,411

FIG. 7

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20! CONTROLLER 200 3 I93 t 3 M $5 FIG. I2

U.S. Patent Dec. 30, 1975 Sheet 70f 12 3,929,411

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247 FLI' 243 254 259 263 q 256 5|2o 5l2b US. Patent Dec. 30, 1975 Sheet 9 0f 12 3,929,411

FIG. I7

U.S. Patcant Dec. 30, 1975 Sheet 10 of 12 3,929,411

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430 424 25 FIG, 2|

US Patent Dec. 30, 1975 Sheet 11 of 12 3,929,411

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mmw Nww MN 6E U.S. Patent Dec. 30, 1975 Sheet 12 of 12 3,929,411

FIG. 23

MOTOR FIG. 24a

SAMPLE TRANSFER DEVICE AND METHOD FOR ANALYTICAL SYSTEM ment for pretreating a sample of water by a chemical treating procedure, such as filtration, distillation, extraction, or color development, and then automatically performing a quantitive analysis of the samples metallic and non-metallic contents by using an analyzer (or detector), for example, for the atomic absorption method or absorption spectrometry.

With the environmental destruction attracting more and more serious attraction, close monitoring of air and water pollution has been urgently called for. For the detection of water pollution and quantitative analysis of water quality, a number of methods are known. Most popular among them, in Japan, are the Testing Methods for Waste Water from Industrial Plants set forth in Japanese Industrial Standards K0102-l97l, modified to conform to the Environmental Standards Concerning Water Pollution established by the Government on the basis of the Basic Law against Public Nuisances. [Other known methods include the Testing Methods for Industrial Waste Water, JlS-KOlOl, the methods defined in the Water-works Law (the Ministerial Ordinance Concerning Water Standards), and the Federal Water Quality Administration methods of the U.S.]

The 118 methods, all designed for manual control, are characterized in that each sample to be handled ranges in volume from ml to 200 ml (or even 500 ml in some cases). From the viewpoint of the conveyance of samples in such volumes, the conventional methods have not proved satisfactory for the reasons to be explained later. Establishment of a new conveyance system has, therefore, been urgently needed for the perfection of automatic chemical analyses.

Characteristics features of existing features of existing automatic analyzers will now be briefly discussed with a primary emphasis laid on the conveyance of samples in ordinary pretreatment equipment.

One of the method uses a continuous flow divided by air bubbles into small-quantity portions. Wherein a reagent line merges with a main sample line and an air line is open into the sample line downstream of said merging point of the reagent line. All these lines are made of elastic material and the sample line and associated lines are squeezed by a squeeze pump having rollers to convey the contents forward, thereby air bubbles equidistantly join the flow of sample-reagent mixture to divide the same into equal portions. Thenceforth the sample-reagent mixture and air bubbles alternately form a stream and move altogether through the main sample line. This method has the following limitations. The sample pipe to be used must have an inner diameter small enough to avoid the disappearance of air bubbles therein, and this places an important limitation upon the quantity of the sample that can be handled. The arrangement is not adapted for such chemical treatment as extraction and dissolution of solids. The inside diameters of the lines which may be chosen are actually limited and only a few sizes are available. This confines the mixing ratio of the reagent and sample within a certain range. The pipes to be used must be elastic enough to endure squeezing and must be chemically stable to the sample and reagent to be encoun- 2 tered. Because of these limitations, some special method must be developed and adopted.

Another known method consists of retaining a sample in a container chemically treating the sample, and then transferring the sample to another place where it is to be subjected to another chemical treatment, either by moving the vessel or drawing up the sample by suction into the pipetter and discharging the same into another vessel. This method also has some limitations. It is impossible in this method to perform such chemical operations as extractive filtration, and distillation. The volume that the pipetter can handle is limited. The fact that the reaction vessels have to be moved together makes it necessary to handle only a small quantity of sample or even to adopt a special analytical procedure. The moving part of the equipment tend to be complicated in structure and increased in size. The sample is exposed to the atmosphere.

A third method known in the art is to convey a sample gravitationally by natural dropping. This method is characterized by the retention of the sample in a vessel during its chemical treatment and by the dependence upon natural downflow by gravity for the transport of the sample and the like. In, this arrangement, the transfer lines must be held as vertically as possible and therefore the components parts that may be used are limited. Also a variety of samples cannot be smoothly handled. Each border of each reaction tank or the like requires a valve. To reduce the resistance of the pipes and valves is of value in facilitating the transport of the sample but brings a penalty of increased dead space, which in turn may cause undesirable intermingling of different samples when they are to be analyzed in succession.

From the standpoint of transport of samples, the existing automatic analyzers, classified by features into three types, have so far been briefly described.

The present invention has been perfected with the view to eliminating the foregoing disadvantages of the prior art equipment, and has for an object to provide a large-capacity apparatus for chemical treatments adapted for practicing a novel method of transporting fluids and capable of chemically analyzing many different samples.

Another object of the invention is to provide an apparatus for chemical treatments capable of automatizing all of the chemical analytical procedures that can be manually performed.

Still another object of the invention is to provide an apparatus for chemical treatments which can be increased in capacity and easily adapted for modifications in analytical procedures.

A further object of the invention is to provide an apparatus for chemical treatments capable of handling solid samples as well as fluid ones, with the system hermetically sealed.

Thus, according to the present invention, an apparatus for chemical treatments is provided which comprises closed vessels, groups of lines and selectively openable valves provided on the upper and bottom parts of the vessels for the conveyance of sample, an atmospheric-pressure gas source, an increased-pressure gas source, and a reduced-pressure gas source, said sources being communicated with said valve groups, one for each, said valve groups being selectively operated to control the pressure of the atmosphere in said vessels so that the sample can be transferred from the outside into the vessels or vice versa.

The foregoing and other objects and features of the invention will appear more fully from a reading of the following description taken in connection with the accompanying drawings, in which:

FIGS. 1 and 2 are diagrammatic views illustrating the conveyance of sample by a prior art technique;

FIGS. 3 and 4 are schematic sectional views of an automatic analyzer of a known type;

FIG. 5 is a schematic sectional view of an automatic analyzer of another known type;

FIg. 6 is a schematic view explanatory of the principle of fluid conveyance for the chemical apparatus according to this invention;

FIG. 7 is a schematic view illustrating connections for the apparatus of the invention;

FIG. 8 is a schematic view of a unit equipment of the apparatus according to the invention;

FIGS. 9 through 21 are schematic views of other unit equipments according to the invention;

FIG. 22 is a schematic view of an arrangement for chemical treatments embodying the invention; and

FIGS. 23 and 24a are diagrammatic sectional view of other forms of unit equipments embodying the invention and FIG. 24b is a sectional view along the line XXIVb-XXIVb of FIG. 24a.

Before explaining the present invention with reference to embodiments thereof shown in the drawings, the three methods employed in the existing automatic analyzers will now be described more definitely by referring to FIGS. 1 to 5.

FIGS. 1 and 2 schematically show the concept of the first prior method using a continuous flow divided by air bubbles into small-quantity portions. A reagent line 7 merges with a main sample line 6 at a junction 9, whereas an air line 4 is open into the sample line at a junction 10. A plurality of rollers 11, 11', are connected with chains 12 to constitute a squeeze pump, generally indicated at 13, which is driven in the direction indicated by an arrow in FIG. 2, so that the sample line 1 and the associated lines can be squeezed to convey the contents forward.

Since the pump 13 squeezes the pipes at a constant speed, the quantities of the sample and other fluids that flow through them depend primarily upon the inner cross sectional areas of the respective lines. Now it is assumed that a sample 1 runs in the sample line 6, a reagent 2 in the reagent line 7, and clean air 4 in the air line 8. The reagent 2 first merges into the sample 1 at the junction 9 to form a sample-reagent mixture 3, and then air bubbles 5 enter the mixture at the junction 10. The mixing ratio of the sample 1 to the reagent 2 is governed by the ratio of the inner cross sectional area of the sample line 6 to that of the reagent line 7. The air bubbles 5 equidistantly join the flow of the sample-reagent mixture 3 at the intervals dictated by the ratio of the inner cross sectional area of the air line 8 to the sum of the inner cross sectional areas of the sample line 6 and reagent line 7, thereby dividing the sample-reagent mixture 3 into equal portions. Each of the air bubbles 5 serves as a barrier wall to avoid intermixing of the adjacent sample-reagent mixture portions. Thenceforth the sample-reagent mixture 3 and air bubbles 5 alternately form a stream and move altogether through the main sample line 6.

In the manner described a reagent can be added at a suitably controlled rate to a continuous flow of sample, and a desirable period of time for a chemical reaction can be obtained through a judicious choice of line length. These lend themselves fundamentally to the automatization of chemical treatments. Because it permits chemical treatments of a sample in the course of transport through a sample line, the method renders it possible to extremely simplify the construction and reduce the size of the equipment for pretreatments of the sample. The reagent and sample which run through fluidtightly sealed lines, cannot be contaminated by any outside source. On the other hand, the method has certain limitations. If any bubble keeping apart two sample-reagent mixture portions of different compositions should break, the two liqud portions would be intermingled, thus interrupting the testing procedure. For this reason the sample pipe to be used must have an inner diameter small enough to avoid the disappearance of air bubbles therein. Practically the upper limit of the diameter is about 5 mm, and this places an important limitation upon the capacity of the sample line, or the flow rate of the sample that can be handled. In addition, the arrangement is not adapted for such chemical treatments as extraction and dissolution of solids. The inside diameters of the lines which may be chosen are actually limited and only a few sizes are available. Consequently the mixing ratio of the reagent and sample is confined within a certain range. The pipes to be employed must be elastic enough to endure squeezing and must be chemically inert to the sample and reagent to be encountered. Because of these requirements, some special method must be developed and adopted. Thus, as compared to other approaches, the method has major limitiations in limitations chemical analyses involved and in the accuracy or reliability of the results.

FIGS. 3 and 4 schematically represent the concept of the second known method consisting the steps of retaining a sample in a container, chemically treating the sample, and then transferring the sample to another place where it is to be subjected to another chemical treatment, either by moving the vessel or drawing up the sample by suction and discharging the same into another vessel. As shown, reaction vessels 26a, 26b, 260 are connected with chains 27 in an orderly manner and are moved stepwise by drives (not shown) in the direction indicated by an arrow. A pipetter, designated 28, is capable of drawing up by suction the contents of a reaction vessel or discharging the contents into an empty vessel through a nozzle 29 equipped with drives (not shown) for its vertical and horizontal movements. A dispenser 24 is operatively connected to two valves 25, so that a reagent 22 from a reagent bottle 33 can be admitted into a reaction vessel via lines 31, 32 and through a nozzle 30 equipped with drives (not shown) for its vertical movement. The nozzle 30 may be independent of the nozzle 29 or may be connected thereto with a bridging tube 34.

On an automatic analyzer of the type described, the sample can be transferred from one place to another where another chemical operation is to be performed, in either of two ways. One way is to cause the pipetter 28 to draw up by suction the contents of a reaction vessel (e.g., the vessel 26b) by way of the nozzle 29,

and then move the nozzle 29 to a point above another reaction vessel (e.g., 26c) and allow it to discharge the liquid into the latter vessel. The other is to take up the nozzles 29, 30 of the pipetter 29 and dispenser 24 from the reaction vessel and move the group of reaction stepwise by drives in the direction indicated by an arrow- (that is, from the positions shown in FIG. 3 to those in FIG. 4). In either case, the reagent 22 can be added to the sample 21 by means of the dispenser 24 and the chemical reaction time can be controlled by adjusting the time intervals for the horizontal movement of the pipetter nozzle 29 or for the movement of all the reaction vessels. These possibilities provide bases for the automatization of operations for chemical analyses.

According to the method, a chemical treatment is carried out with the sample retained in a reaction vessel and the transfer of the sample is accomplished by moving the vessel containing the same. This presents an advantage of simplicity in the analytical operation and hence in the fundamental construction of the apparatus, and provides an additional advantage of the containment of different samples in independent vessels which precludes intermingling of the samples. On the other hand, it is impossible with this arrangement to perform such chemical operations as extractive filtration, and distillation. The volume that the pipetter can handle is limited. The fact that the reaction vessels have to be moved together makes it necessary to handle only a small quantity of sample, or even to adopt a special analytical procedure. The moving parts of the equipment tend to be complicated in structure and increased in size. Among the other disadvantages is the exposure of the sample to the atmosphere.

Flg. schematically represents the concept of the third method known in the art in which a sample is conveyed gravitationally by natural dropping. Reaction tanks 48, 49 are communicated to each other by pipes 50, 51 open in the respective tanks, with a valve 53 for shutoff purpose installed between the two pipes. The tanks 48, 49 are formed with vents 57, 58, which are open in the atmosphere. A sample storage tank 56 is communicated to the upper part of the reaction tank 48 with pipes 52, 55, which are open in the respective tanks and are separated by a valve 54 installed midway. A dispenser 43 is operatively connected to valves 44 to enable the reagent 41 from a reagent bottle 47 to flow into the reaction tank 48 via pipes 45, 46.

Opening the valve 54 allows the sample to run down gravitationally, at a controlled rate, into the reaction tank 48 through the pipes 52, 55. Meanwhile a given quantity of the reagent 41 is added to the sample in the reaction tank 48 by means of the dispenser 43, the addition being followed by a certain waiting period. These functions constitute some requisites for chemical hereunder. The method of transporting a sample in the apparatus for chemical treatments in accordance with this invention is to convey the sample by controlling the atmosphere surrounding the same, that is, by changing it pressure to atmospheric, positive or negative one. Here, numerals 61, 73 indicate reaction tanks wherein sample mixtures are retained and subjected to chemical treatments. They are equipped with auxiliary means so that they can perform practically analogous functions. In the upper parts of the reaction tanks 61, 73 are open sample lines 62, 74, the other ends of which are connected to sampleline valves 63, 75 for opening and closing the lines. Sample-drain pipes 64, 76 are open in the lower parts of the reaction tanks 61, 73 and, on the other ends of these pipes, sample-line valves 65, 77 and waste-liquid line valves 72, 84 are installed as shown. The sample-line valves 65, 75 are connected via sample pipe 741. One end of each of manifolds 66, 78 is open in the upper parts of the reaction tanks 61, 73. Three ports in the other parts of the manifolds are provided with atmospheric-pressure line valves 67, 79, increased-pressure line valves 68, 80, and reduced-pressure line valves 69, 81. Reagent inlet pipes 70, 82 are open in the upper parts of the reaction tanks 61, 73,

analyzing operations. If necessary, the sample-reagent mixture 42 is conveyed by gravity through the pipe 50, valve 53, and pipe 51 into the lower reaction tank 49.

This third method is characterized by the retention of the sample in a vessel during its chemical treatment and by the dependence upon natural downflow by gravity for the transport of the sample and the like, which eliminates power requirement. This means, however, that the transfer lines must be held as vertically as possible and therefore the component parts that may be used are limited. A variety of samples cannot be smoothly handled. Each border of each reaction tank or the like requires a valve. To reduce the resistances of the pipes and valves is of value in facilitating the transport of the sample but brings a penalty of increased dead space, which in turn may cause undesirable intermingling of different samples when they are to be analyzed in succession.

With reference specifically to FIG. 6, the fundamental principle of the present invention will be described and reagent inlet valves 71, 83 are installed at the other ends of pipes 70, 82.

The reaction tanks 61, 73 equipped with the groups of pipes and valves above described constitute closed reaction tank units 501, 502, respectively.

For their operations these reaction tank units are connected to necessary pipe groups and necessary external sources. A sample pipe 85 is connected to the sample-line valve 63 and is in communication with a sample reservoir (not shown) at the atmospheric pressure or an increased pressure. Atmospheric-pressure pipes 86a, 86b are preferably open in the atmosphere through filters or are communicated with an inert-gas reservoir (not shown) at the atmospheric pressure, because the reaction tank units form closed systems. Increased-pressure pipes 87a, 87b are likewise in communication through filters to a clean-air or inert-gas source (not shown) under pressure (positive pressure) of 0.0ll kg/cm G. Reduced-pressure pipes 88a, 88b are connected to a reduced-pressure (negative pressure) source (not shown), desirably at a pressure between 0.01 and 0.5 kg/cm G. Waste-liquid pipes 89a, 89b communicate with a suction source (not shown) at a pressure between 0.01 and 0.5 kg/cm G, which constantly draws up by suction the liquid or gas that flows through the pipes.

The procedure for feeding samples to these reaction tank units will now be explained. Unless otherwise specified, it should be understood that all valves in the vavle groups are closed. In order to introduce -a sample into the reaction tank 61, it is only necessary to open the sample-line valve 63 and atmospheric-pressure line valve 67 if the sample reservoir is kept under pressure or, if the pressure in the reservoir is atmospheric, the sample-line valve 63 and reduced-pressure line valve 69 have only to be opened, so that the pressure in the reaction tank 61 is reduced to attract the sample into the vessel. In either case, all valves are closed after a predetermined amount of sample has been fed to the reaction tank 61 and, immediately thereafter, the atmospheric-pressure line valve 67 is temporarily opened to maintain the atmospheric pressure in the tank. Transference of the sample from the reaction tank 61 to the tank 73 may be accomplished in either of twc ways. One is to enable the reaction tank 73 to have a passive function (after which the procedure is hereinaf ter called the passive transference). In this procedure the increased-pressure line valve 68, sample-line valves 65, 75, and atmospheric-pressure line valve 79 are opened. Now that the sample-line valves between the two reaction tanks are open, the sample-line is open, too, and the sample in the reaction tank 61 is forced down into the reaction tank 73 by the increased pressure (positive pressure) being exerted from the above liquid level in the tank 61. The sample admitted into the reaction tank 73 is, of course, kept at the atmospheric pressure. If it is assumed that the flow passage between the two reaction tanks is equivalent to a pipe 2.4 mm in inside diameter and cm in length, then 100 ml of water will be transferred from the former to the latter in about 20 seconds by simple exertion of a positive pressure of about 0.1 kg/cm on the increasedpressure pipe 87a.

The other procedure is to permit the reaction tank 73 to have an active function (hereinafter called the active transference). This time the atmospheric-pressure line valve 67, sample-line valves 65, 75, and reduced-pressure line valve 81 are opened. Communication is thus established between the two reaction tanks and, because the pressure in the tank 73 is reduced (negative) whereas the sample in the tank 61 is at the atmospheric pressure, the sample is conveyed from the tank 61 to 73. If the passage and conditions for the conveyance of the sample are the same as in the passive transference, then a negative pressure of about 0.1 kg/cm applied to the reduced-pressure pipe 88b will be sufficient to effect the conveyance. Here it is appreciated that the passive transference to the reaction tank 73 means the active transference from the tank 61 and vice versa. Therefore, the afore-described method of supplying the sample to the reaction tank 61 with the reduced-pressure line valve 69 opened corresponds to the active transference to the tank 61. Whichever procedure is followed, the pressure in the vessel after the supply of the sample is kept positive or negative for an excess period of time, so that any sample that may have adhered to the surrounding wall of the passage is blown off clearly by the stream of air or inert gas. Consequently there is no possibility of undesirable intermingling of different samples along any relatively long passage. This is another major advantage of the transference by this procedure. When the sample in the reaction tank 73 is to be transferred to some other place, the increased-pressure line valve 80 and sampleline valve 77 have only to be opened in order that the reaction tank 73 may accomplish the active transference. If any waste material is to be delivered out for abandonment from either the reaction tank 61 or 73, it is merely necessary to open the waste-liquid line valve 72 or 84 and atmospheric-pressure line valve 67 or 79 as the case may be, and then drain the waste material into the waste-liquid line 89a or 89b which is ready to draw in the waste by suction. As an alternative to this passive transference for the either tank, the active procedure may be resorted to by opening the waste-liquid line valve and increased-pressure line valve of the particular tank.

The reaction tank units 501, 502 are provided with reagent lines (not shown) through which and the reagent inlet valves 71, 83 a reagent or reagents can be supplied from reagent bottles. The reagent or reagents can be added to the samples in the tanks by the passive or active transference and with the use of the reagent inlet valves 71, 83. This, when combined with the contollability of the length of time for which the sample is retained in either reaction tank or the both, will provide the basis for automatization of treatments for chemical analyses.

It is to be noted that the sample pipe 741, if out off midway, will provide two identical reaction tank units 501, 502. Each of these units comprises a reaction tank, a sample pipe (for sample feeding) and a valve installed on the upper part of the tank, a sample pipe (for sample discharging) and a valve on the lower part, and a group of valves and lines provided above the vessel to make the pressure therein positive, atmospheric, or negative for the purpose of sample conveyance. Considering these reaction tank units as unit equipments each combining active and passive functions, it follows that the units can be connected both in series and parallel. Any unit equipment may be disconnected from, or may be added to, any of complex combinations of unit equipments, without affecting the function of the original combination and that of the automatic controls including the valves.

Aside from the reaction tank units taken as examples of unit equipments in the foregoing description, such other chemical apparatus as filters, aerators, thermal distillers, thermal concentrators, agitators, pH-adjusters, extractors, separators, and dissolvers may fall into the domain of units of which the present invention is equally applicable. If the sample container of any such units enumerated above is combined with groups of pipes and valves for sample conveyance and groups of valves and pipes for making the pressure in the vessel positive, atmospheric, or negative so as to convey the sample just in the same way as with a reaction tank unit, then such a chemical apparatus will be interchangeable with any of the reaction tank units.

Briefly stated, combination of the automatic control of such unit equipments with that of sample conveyance provides automatic control of every operation for chemical treatment.

Serial connection of reaction tank units has already been described in connection with the fundamental principle of the present invention. Next, parallel connection of the reaction tank units in an embodiment of the invention and the procedure for sample transference involved will be explained with reference to FIG. 7. For the sake of simplicity, reagent inlet pipes and valves are omitted from all of the reaction tank units illustrated. A first reaction tank unit 503, like the tank units already described, comprises a reaction tank 91, sample pipe 92, sample-line valve 93, sample-drain pipe 94, atmospheric-pressure line valve 95, increasedpressure line valve 96, reduced-pressure line valve 97, and waste-liquid line valve 98. It differs from the reaction tank units 501, 502 in that the sample-drain pipe 94 is not terminated with a sample-line valve but is connected to a tee 116. Second and third reaction tank units 504, 505 are quite similar to the units 501, 502 shown in FIG. 6. Smaple-line valves 103a, l03b of these reaction tank units are communicated with a tee 117, so that the tank units 504, 505 are on equal terms with the first unit 503. A fourth reaction tank unit 506 comprises a reaction tank 108, sample pipe 109, sample-line valve 111, atmospheric-pressure line valve 112, increased-pressure line valve 113, reduced-pressure line valve 114, and waste-liquid line valve 115. The sample pipe 109 communicates to the tee 117 instead of a sample-line valve. The tee 117 is in communication with the sample-line valves 103a, 103b. Stated differently, the second reaction tank unit 504 and the third unit 505 are disposed between and in parallel to the first and fourth units 503, 506. Description of the pipe groups and external supply sources will be omitted hereinafter because, unless otherwise stated, they are in essence the same as those already described in connection with the fundamental principle of this invention.

It is now assumed that in operations involving threestep chemical treatment the treating time required for the first or third step is a half of the period for the second step. In this case the reaction tank units are desirably connected as illustrated in FIG. 7. Unless otherwise stated, all valves are construed to remain closed. First, the sample is introduced into the reaction tank unit 503 by the active transference, that is, by opening the sample-line valve 93 and reducedpressure line valve 97 and thereby reducing the pressure in the tank 91. After the introduction, the atmospheric-pres sure line valve 95 is once opened to increase the pressure of the sample to the atmospheric level, and then the first-step chemical treatment is carried out. Next, the sample is transferredto the second reaction tank unit 504. As noted already, the transference may be accomplished in either of two ways. One method is, in this case, the passive transference to the reaction tank unit 504, whereby the increased-pressure line valve 96, sample-line valve 101a, and atmospheric-pressure line valve 104a are opened to place the sample inside the reaction tank 91 under an increased pressure. The other is the active transference to the same unit 504 whereby the atmospheric-pressure line valve 95, sampleline valve 101a, and reduced-pressure line valve 106a are opened. In the subsequent increased-pressure or reduced-pressure operations with the other reaction tanks orsample containers to be mentioned later, it is to be noted that, unless otherwise specified, the atmospheric-pressure line valve is once opened to maintain the pressure in the vessels at the atmospheric level. Here the second-step chemical treatment is effected. Since the time required for the second step treatment is twice as much as for the first step, the first reaction tank unit 503 is allowed to repeat the first-step treatment with another sample while, at the same time, the second step is in progress. The first sample is then transferred to the third reaction tank unit 505 in the same manner as when it was conveyed from the first unit 503 to the second 504, except that the sample-line valve 10111 is employed this time. During this, the second-step treatment is repeated. As will be explained later, the method of sample transference is limited to one, passive or active, depending upon the type of unit equipment to be employed for a particular chemical treatment or upon the type of sample or reagent to be handled. The sample is then transferred from the second reaction tank unit 504 to the fourth unit 506. Again, two alternatives are open. One is the passive transference to the unit 506, whereby the increasedpressure line valve 105a, sampleline valve 103a, and atmospheric-pressure line valve 112 are opened to convey the sample. The other is the active transference whereby the atmospheric-pressure line valve 104a, sample-line valve 103a, and reduced-pressure line valve 114 are opened for the conveyance purpose. In this stage the third-step chemical treatment is performed. The increased-pressure line valve 113 and sample-line valve 111 are opened and, by this active transference from the unit 506, the sample is transferred elsewhere. In order to transfer the sample from the reaction tank 99b to the tank 108, it is simply necessary to use the sample-line valve 1013b and resort to the passive or active transference from the reaction tank unit 506 in the manner above described. If any undesired residue (such as the washings to be described later) is found in any reaction tank unit, it may be discharged into the waste-liquid line by opening the waste-liquid line valve and following the procedure for passive or active transference from the particular tank unit.

Although the example given above uses a pair of reaction tank units for parallel connection, it should be obvious from the description of the principle of this invention that more reaction tank units may be connected in parallel or, as a further alternative, groups of serially connected units may be connected altogether in parallel.

In the foregoing description the reaction tank units have been regarded as components of a unit equipment. Now that equipments having separate functions of chemical treatments will be considered.

One of such unit equipments is a unit for the addition of a reagent, as schematically illustrated in FIG. 8. A sample pipe 132 is open in the upper part of a reaction tank 131 and is connected at the other end to a sampleline valve 133. A sample-drain pipe 134 which is open in the lower part of the reaction tank 131 is communicated with a sample-line valve 135 and a waste-liquid line valve 141. A manifold 136 which is open in the upper part of the tank communicates to an atmosphericpressure line valve 137, an increased-pressure line valve 138, and a reduced-pressure line valve 139. A reagent line that extends from a reagent bottle (not shown) through valves 142, which are operatively connected to a dispenser 143, terminates in the form of a reagent pipe 1410, which in turn is open in the upper part of the reaction tank 131. If agitation is required, an agitator consisting, for example, of an agitation blade 144 inside the tank and an external magnetic stirrer 145, may be installed. In this way a reagent-addition unit 507 is constructed.

The operation, function, and performance of this unit 507 will be described later hereunder. Here again the description of the lines and external supply sources required for the operation will be omitted because they are essentially the same as those which have already been described. Also, unless otherwise stated, it should be appreciated that all valves are normally closed and the reaction tank or other vessel to be described later is hermetically sealed. The same applies to all of the equipments to be described later and, therefore, these provisos will be omitted for brevity from the the following description.

, First, the sample-line valve 133 and atmosphericpressure line valve 137 or reduced-pressure line valve 139 are opened to admit the sample into the reaction tank 131 by the passive or active transference to the reaction tank unit 507. After the transference, the atmospheric-pressure line valve 137 is opened for some time to maintain the sample at the prevailing atmospheric pressure. Next, while the valve 137 is kept open, the valves 142 operatively connected to the dispenser 143 are manipulated, so that a given amount of the reagent can be added to the sample by way of the reagent pipe 140. This may be effected, if necessary,

1 1 while the magnetic stirrer 145 is being driven and the sample-reagent mixture is being agitated by the blade 144.

For the addition of the reagent, a valve such as indicated at 71 in FIG. 6 may be employed provided that the given amount of the reagent can be measured into the tank by some suitable means. Importantly, the valve to be used must be capable of hermetically closing the reagent-addition unit, even on a temporary basis. Also it should be clear that, while one type of reagent is handled in the unit being described, many different reagents may be added, instead, in a similar way.

After the reagent and sample have thoroughly reacted with each other (usually with the atmosphericpressure line valve 137 closed, although the valve must be kept open for certain reaction systems), the atmospheric-pressure line valve is closed and agitation is discontinued. In order to transfer the reaction product to some other place, either the passive or active transference from the reaction tank unit 507 is effected by opening the sample-line valve 135 and atmosphericpressure line valve 137 or increased-pressure line valve 138. If useless sample is to be discarded, the waste-liquid line valve 141 is used in lieu of the sample-line valve 135.

Another example of unit equipment is a fixed-quantity sampling unit 508, as schematically shown in FIG. 9. A sample-line valve 153 is installed in communication with a sample pipe 152, which in turn is open in the upper part of a container 151. A sample-drain pipe 154 open at one end in the lower part of the container 151 is communicated at the other end with a sample-line valve 155 and a waste-liquid line valve 159. In communication with a manifold 156 which is open in the upper part of the container 151, there are installed an atmospheric-pressure line valve 157 and an increased-pressure line valve 158. A nozzle 160 is open in a suitable position inside the container via a gastight seal (not shown) capable of moving up and down in the upper part of the vessel. The other end of the nozzle communicates to a line 162 through a valve 161. Such is the construction of a fixed-quantity sampling unit 508. The line 162, inside of which is kept at a reduced pressure by some suitable means, attracts fluid, either liquid or gas.

The operation of this fixed-quantity sampling unit 508 will now be explained. The sampleline valve 153 and valve 161 are opened first. This results in a reduced pressure inside the container 151, and the sample begins to be conveyed through the pipe 152 into the vessel. Once the sample level has reached the opening of the nozzle 160, any excess of the sample is drawn up by suction into the line 162 through the nozzle 160 and valve 161, with the consequence that the liquid level of the sample 163 is kept constant. Even if the sample level has temporarily exceeded the opening of the nozzle 160, the excess sample will be taken up by the nozzle 160 when the sample-line valve 153 is closed while, at the same time, the atmospheric-pressure line valve 157 is opened. As a result, the liquid level of the sample 163 will be maintained constant. The opening position of the nozzle 160 may be preset so that a predetermined amount of the sample 163 can be held within the container. When considering this sampling method with the valve 161 replaced by a reduced-pressure line valve, it is appreciated that the method is tantamount to the active transference to the sampling unit 508. The measured amount of the sample 163 is either transferred to some other place or abandoned by the active transference from the unit by opening the increasedpressure line valve 158 and sample-line valve or waste-liquid line valve 159.

This fixed-quantity sampling unit may be utilized to collect the supernatant fluid from a solution containing sediments, in which case the opening position of the nozzle has only to be chosen so that the portion of the liquid which tends to be relatively easily clarified can be collected.

The third example of unit equipment is a dilution unit, either of a photoelectric type or an electric conductivity type, as schematically represented in FIG. 10 or 11, respectively. The unit shown in FIG. 10 will be described first. In the upper part of a reaction tank 171 is open a sample pipe 172 which is equipped with a sample-line valve 173. In the lower part of the tank 171 is open a sample-drain pipe 174, which in turn communicates to a sample-line valve 175 and a waste-liquid line valve 182. A manifold 176 open at one end in the upper part of the tank 171 is also in communication with an atmospheric-pressure line valve 177, an increased-pressure line valve 178, and a reduced-pressure line valve 179. From the bottom of a reagent bottle 186, a reagent pipe 180 extends downward through a valve 181 and opens in the reaction tank 171. Further, along both sides of the tank there are located a light source 183 and a light-beam detector 184, in positions opposite to each other and in such a way that they can be moved up and down by some suitable means (not shown) with respect to the tank 171. Signals from the light-beam detector 184 are sent to a controller 185, so that the sample-line valve 181 can be opened or closed depending upon the presence or absence of the detection signals. Such is the construction of a dilution unit 509.

The unit is operated in the following manner. It is assumed that the reaction tank 171 is filled with a given quantity of sample by the procedure already described in connection with the reagent-addition unit, and that the sample is to be diluted, for example, with water. The light source 183 and light-beam detector 184 are located on a level equal to that of the liquid after dilution. The optical instrument of this type detects the deflection of the path of a light beam from the source 183 due to the difference between air and the sample (liquid), in terms of ON-OFF signals on the detector 184. The controller 185 is so adjusted that, when there is a predetermined amount of the sample in the reaction tank 171, the valve 181 is kept open and the reagent (mere water in this case) is allowed to drop from the bottle 186 into the reaction tank 171 until the liquid level of the sample in the tank comes up to the light path. In this manner the reagent (or water) is added only when there is a predetermined amount of the sample in the reaction tank or, in other words, dilution to a predetermined level is accomplished. In exemplary operations, the errors in dilution were in the range of plus or minus 0.2% per 100 ml of the diluted solution.

The arrangement shown in FIG. 11, or the electric conductivity type, differs from the type of FIG. 10 in the method of detecting the liquid level after the dilution as specified. The type of FIG. 10 detects the level optically, whereas that of FIG. 11 detects it by means of an electrode that forms a part of an electric circuit. The

' electrode, indicated at 203, consists of a glass tube or the like and two wires of platinum or the like insulated and enclosed in the glass. It is vertically movable in the upper part of a reaction tank 191 while hermetically sealing the tank. A controller 204 comprises the electric circuit including the electrode 203 as one of its components, and functions so that, when there is the sample to be diluted in the reaction tank 191, the controller cooperates with the electric circuit to open a reagent inlet valve 201 and admit the reagent (e.g., water) into the reaction tank and, when the liquid level of the diluted sample has reached the electrode 203, it closes the reagent inlet valve 201. The electric circuit is used to detect the difference between the electric conductivities of the air and the sample between the element wires of the electrode 203. In other words, the circuit is of the electric conductivity type. The components described above are assembled to form a dilution unit 510.

The electric conductivity system of the dilution unit 510 works in the manner now to be described. It is assumed that the reaction tank 191 is prefilled with a given amount of the sample and that the sample is to be diluted to a certain volume with the addition, for example, of water. The electrode 203 is installed at the height corresponding to the liquid level after the dilution. The controller 204 opens the reagent inlet valve 201 in response to a signal from the outside, so that the reagent (or water in this case) is admitted into the reaction tank 191. If necessary, the sample may be agitated by an agitator (not shown). Initially the electric conductivity between the electrode wires is zero (because air is an insulator) but, as the liquid surface of the sample having a certain specific conductivity comes into contact with the electrode wires, the controller 204 closes the sample inlet valve 201, thus completing the dilution. In exemplary experiments, the accuracy of dilution with this unit 510, as well as with a dilution unit of a high-frequency transmission type, was less than plus or minus 0.2% for the sample volume of 100 ml, where a reagent inlet pipe 200 having an inside diameter of 2.4 mm was employed.

Dropwise introduction of the reagent into the reaction tank 171 may be effected in two ways; either by opening'only the atmospheric-pressure line valve 177 and allowing the reagent to flow down by gravity, or by opening only the reduced-pressure line valve 179 and thereby reducing the pressure in the reaction tank 171.

The fourth example of unit equipment is a washing unit, as schematically shown in FIG. 12. It is more practical to employ this washing unit as a washer for a reaction tank or container of another unit equipment than to consider it as a unit equipment. However, for the simplicity of explanation, it is taken here as an independent unit equipment. It will be seen from the foregoing description about the three different unit equipment that those units have many parts in common. The illustration and description of the common parts do not appear essential for the explanation of the functional principles of the unit equipments and, therefore, will be omitted hereinafter.

14 4 change-over valve 219. This valve is so designed that when it remains closed as well as other valves, the reaction tank 211 is hermetically sealed. Alternatively, another valve (not shown) may be installed midway the washing nozzle 217 instead of using the change-over valve 219 of the construction just described above. In the arrangement shown, changing over the valve 219 can establish communication between the washing nozzle 217 and either a washing-solution A line 220 or a washing-solution B line 221. Those lines 220, 221 are connected to respective washing-solution reservoirs (not shown) with or without an additional pressure applied to the liquids therein. These components make up a washing unit 511.

The function of this washing unit 511 and the washing method adopted will be described below. By way of explanation the inner wall of the reaction tank 211 is assumed to be contaminated. From the viewpoint of introduction of the washing solution, the washing operation can be carried out in a number of ways. In one procedure, the waste-liquid line valve 213 and atmospheric-pressure line valve 215 are opened to allow the contaminant to drain from the reaction tank 211 into the waste-liquid line (not. shown) wherein the partial vacuum continues to provide suction as well as in the reaction tank. Next, the change-over valve 219 is manipulated (to the position in FIG. 12) where it communicates the washing nozzle 217 to the washing-solution A line 220 at an increased pressure or at the prevailing atmospheric pressure. The washing solution A introduced through the washing nozzle 217 is then scattered by the sprinkler 218 to wash the inner wall surface of the reaction tank and flow down into the waste-liquid line (when, if necessary, the atmospheric-pressure line valve 215 may be closed.) Instead of this washing with running liquid, it is also possible to use the washing solution in a retained state. For this purpose the wasteliquid line valve 213 is closed and the atmosphericpressure line valve 215 is opened so that the washing solution A under pressure or at the atmospheric pressure can be led through the change-over valve 219 and collected in the reaction tank 211. Following the washing, with agitation where necessary, the washings are allowed to drain in either of two ways. The waste-liquid line valve 213 and atmospheric-pressure line valve 215 are opened and the washing are caused to flow down into the waste-liquid line wherein the suction still prevails. Or, the atmospheric-pressure line valve 215 is closed and the increased-pressure line valve 216 and waste-liquid line valve 213 are opened to flow down the washings. If the washing solution A alone cannot wash well, the change-over valve 219 may be manipulated to use the washing solution B, too. Of course, three or more different washing solutions may be used in this manner. For example, in the case of the hydroxides in river water that precipitate on the alkaline side of pH 10 in a reaction tank capable of treating ml of the sample, mere distilled water cannot thoroughly wash the deposits away. It is customary in such occasion to dissolve the deposits with a dilute acid and then wash away the acidic solution with distilled water. In this manner thorough washing is accomplished.

Still another example, the fifth, of unit equipments is hydrogen-ion-concentration (pH)-adjusting unit. FIG. 13 illustrates the unit schematically. For the pH adjustment, usually a commercially available pH meter equipped with an automatic titrator is used. In order to simplify the construction of the reaction tank a com- 

1. AN APPARATUS FOR SUCCESSIVELY TRANSFERRING A PLURALITY OF DIFFERENT LIQUID SAMPLES TO A PLURALITY OF DIFFERENT TREATMENT STATIONS IN AN ANALYTICAL SYSTEM COMPRISING: A FIRST TREATMENT UNIT INCLUDING A FIRST ENCLOSED VESSEL, A SAMPLE INLET CONNECTED TO AN UPPER PART OF SAID FIRST VESSEL AND A FIRST VALVE CONNECTED TO SAID SAMPLE INLET; A SECOND TREATMENT UNIT INCLUDING A SECOND ENCLOSED VESSEL, A SAMPLE OUTLET CONNECTED TO THE LOWER MOST PORTION OF SAID SECOND VESSEL AND A SECOND VALVE CONNECTED TO SAID SAMPLE OUTLET; FIRST CONDUIT MEANS FLUIDLY COMMUNICATING THE LOWERMOST PORTION OF SAID FIRST VESSEL WITH AN UPPER PORTION OF SAID SECOND VESSEL; A THIRD VALVE CONNECTED TO SAID FIRST CONDUIT MEANS; SOURCES OF GASSES AT AN INCREASED PRESSURE, REDUCED PRESSURE AND ATMOSPHERIC PRESSURE FLUIDLY COMMUNICATING WITH UPPER PORTIONS OF SAID FIRST AND SECOND VESSELS THROUGH RESPECTIVE VALVES; AND
 2. The apparatus of claim 1, further comprising a third treatment unit including a third enclosed vessel; second conduit means fluidly communicating the lowermost portion of said first vessel with an upper portion of said third vessel; a fourth valve connected to said second conduit means; a sample outlet connected to the lowermost portion of said third vessel; a fifth valve connected to said sample outlet; said source of gas under pressure fluidly communicating with an upper portion of said first vessel through a valve.
 3. A method for successively transferring a plurality of liquid samples to a plurality of different treatment stations in an analytical system, each treatment station including a hermetically sealed vessel, inlet means located in the upper portion of the vessel and outlet means located in the lowermost portion of the vessel, said method comprising transferring a first liquid sample to a fIrst treatment station, establishing by means of a conduit a fluid communication between the outlet means of said first treatment station and the inlet means of a second treatment station, establishing a pressure differential between the vessel interiors of the first and second treatment stations so that said first sample is transferred by means of said pressure differential from said first treatment station to said second treatment station, and maintaining the pressure differential between said first and second treatment stations after all of said first sample has been transferred to said second treatment station so that portions of said first sample deposited on the walls of the vessel of said first treatment station and said conduit are blown away cleanly with a jet of gas.
 4. The method of claim 3, wherein the pressure differential is established by maintaining the pressure in said second treatment station at substantially 1 atmosphere and increasing the pressure in said first treatment station above 1 atmosphere.
 5. The method of claim 3, wherein the pressure differential is established by maintaining the pressure in said first treatment station about 1 atmosphere and reducing the pressure in said second treatment station below 1 atmosphere.
 6. The method of claim 3, further comprising transferring said first sample from said second treatment station to a third treatment station by means of a pressure differential established between said second treatment station and said third treatment station.
 7. The method of claim 6, wherein a second sample is transferred to said first treatment station prior to the exiting of said first sample from said analytical system.
 8. The method of claim 3, further comprising transferring a second sample to said first treatment station after the first sample has been removed therefrom, and transferring said second sample from said first treatment station to a third treatment station by establishing a fluid communication between the outlet means of said first treatment station and the inlet means of said third treatment station and establishing a pressure differential between the vessel interiors of the first and third treatment stations.
 9. The method of claim 8, further comprising transferring said first sample from said second treatment station to a fourth treatment station arranged in series with respect to both said second treatment station and said third treatment station, and thereafter transferring said second sample from said third treatment station to said fourth treatment station.
 10. The method of claim 9, wherein each sample is transferred from one of the treatment stations to a successive downstream treatment station by establishing a fluid communication between the outlet means of said one treatment station and the inlet means of said successive downstream treatment station and by establishing a pressure differential between the vessel interiors of said one treatment station and said successive downstream treatment station.
 11. The method of claim 9, wherein the residence times of the samples in said second treatment station and said third treatment station are approximately twice the residence time of the samples in said first treatment station.
 12. The method of claim 11, wherein successive samples passing out of said first treatment station are alternately transferred to said second treatment station and said third treatment station.
 13. The method of claim 3, wherein said apparatus is arranged so that said treatment stations define at least one flow path for each sample, each sample travelling down its respective flow path in the forward direction only.
 14. The method of claim 3, wherein said first sample is transferred from said first treatment station to said second treatment station by maintaining the pressure in said second treatment station approximately 1 atmosphere and increasing the pressure in said first treatment station to above 1 atmosphere, sAid process further comprising transferring a second sample from said first treatment station to said second treatment station by maintaining the pressure in said first treatment station about 1 atmosphere and decreasing the pressure in said second treatment station to below 1 atmosphere. 